Is there an easy way to make volumetric clouds for Cycles?
Let's use the Cloud Generator addon to make nice clouds and the new Point Density Texture to render them inside Cycles!


First enable the addon in User Preferences under Object: Cloud Generator.
Switch to Blender Render (the addon does not work under Cycles), add some cubes and turn them into clouds with the addon (the UI is located inside Tool Shelf T under Create > CloudGenerator in Object Mode):





(we won't use the explosion because it's not a cloud and requires a different Cycles shader)

After you choose the cloud type it will generate objects like this:



We are interested in the CloudBounds object and in CloudPoints.
Switch to Cycles Render and if using pre-2.77 Blender version use CPU rendering (Point Density does work on GPU in 2.77+). We need to give the CloudBounds object a Cycles material:



Play with the Radius and Multiply Node to fine tune the shape and density.

Delete all the non-used objects from the scene and make sure there are no Blender Internal materials left. All the CloudBounds should have Cycles materials and all the CloudPoints should be without material and hidden from render.
Add some lighting: Sun Lamp, Hemi Lights. Render:


When you get the hang of it create any shapes you like from differently sized and deformed cubes or some basic geometry.